1. Field of the Invention
The present invention relates to an image processing apparatus configured to restore color image data that has been output as monochromatic image data. More specifically, the present invention relates to an image processing apparatus configured to output color image data as monochromatic image data that can later be restored as color image data, an image processing apparatus control method, a program, and a storage medium therefor.
2. Description of the Related Art
In recent years, users of an image processing apparatus have desired to obtain color image data or a color print product from monochromatic image data or a monochromatic print product.
Suppose a case where a presenter performs a presentation during a business conference using a monochromatic print product distributed to each participant. In this case, the presenter performs the presentation using color presentation data on a screen for a projector (image display apparatus) installed in front of the participants in the conference room.
With this environment, in this case, the participants sometimes refer to the distributed monochromatic print product while looking at the presentation data displayed on the screen. With this environment, the participants would not feel inconvenience during the conference because they can recognize what has been presented by looking at the color presentation data displayed on the display screen even though the distributed material is a monochromatic print product.
However, when the participants looks at the monochromatic print product in their own office or at home, the participants may desire to obtain and use color image data or a color print product from the monochromatic print product, because the monochromatic print product, which does not have sufficient amount or quality of data, may be inconvenient for the participants.
As described above, the market has demanded an image processing apparatus or a method that enables a user to obtain color image data or a color print product from or based on monochromatic image data or a monochromatic print product. The following three conventional methods, for example, can satisfy that demand.
Japanese Patent Application Laid-Open No. 01-197878 discusses a method for printing, on a print paper (recording medium), a bar code describing address data of a server apparatus that stores original color image data. With this method, when the print paper having the bar code is scanned with a scanning unit of a client apparatus (image processing apparatus) connected to the server apparatus directly or via a network, the image processing apparatus refers to the sever apparatus based on the address data described in the bar code. Then, the image processing apparatus reads the original color image data from the server apparatus, and then prints out the read original color image data.
Japanese Patent Application Laid-Open No. 10-126607 discusses a method for printing out original color image, which is described as a bar code, on a print paper. With this method, an image processing apparatus scans and reads the bar code describing the original color image data, and then prints out the read original color image data.
Japanese Patent Application Laid-Open No. 08-279896 discusses a method in which an image processing apparatus searches for and extracts, from color image data, an area whose color is neither white nor black to obtain color data (not color-difference data). In this method, the image processing apparatus generates a bar code describing positional data and color data about each object. Furthermore, the image processing apparatus generates monochromatic image data from the color image data, and prints out the generated monochromatic image data, which has been obtained from the color image data, on a print paper together with the generated bar code. With this method, the image processing apparatus scans the print paper to read the bar code, and generates a color image using the color data described in the bar code.
However, with the method discussed in Japanese Patent Application Laid-Open No. 01-197878, it is necessary to provide and install a server. Furthermore, it is necessary for a user of a client apparatus connected to the server to upload onto the server image data to be printed in the case of a network copy job. Accordingly, under an office environment in which a large amount of data including documents and images is handled, it is inconvenient to store a large amount of image data on the server. Furthermore, in the case of transmitting large-size image data via the network or transmitting a large amount of image data at once via the network, the data communication network may be too busy.
Furthermore, with the method discussed in Japanese Patent Application Laid-Open No. 10-126607, it is necessary to generate a bar code of very-large-size color image data. Accordingly, the size of a bar code (including a two-dimensional bar code) may become very large.
More specifically, the size of color image data captured with a digital camera having an image sensor capable of capturing image data with a six million-pixel resolution for each color of red, green, and blue (RGB) may be as large as around 18 megabytes. On the other hand, the data amount of a bar code printed in an entire recordable area of an A4 size print paper can be around 1 kilobytes. That is, the ratio of the size of such color image data to the size of such a bar code is about 18,000:1.
As described above, Japanese Patent Application Laid-Open No. 08-279896 discusses a method in which an image processing apparatus searches for and extracts, from color image data, an area whose color is neither white nor black to obtain color data (not color-difference data). Here, the color data includes both luminance data (density data or monochromatic data, which is equivalent to luminance data) and color-difference data. Accordingly, the size of the color data can become large.
Thus, the actual size of a bar code generated based on such large-size color data may become very large.
It is desired by the market to address the above-described problems. More specifically, an image processing apparatus is desired and useful that is capable of reducing an amount of data required for converting image data, which has been output as monochromatic image data generated based on an original color data, into color image data later.